In this continuing study of palate morphogenesis and effects of teratogens in causing cleft palate, the proposed research will be to determine whether skeletal muscle, smooth muscel-like or microfilamentous contractile systems in the palate play a role in shelf movement. Morphological studies will be continued to help characterize the observed contractile systems in regions 1, 2 and 3. Anti-smooth muscle myosin will be incubated with palatal sections to localize smooth muscle-like or microfilamentous-rich regions. Inhibitors of activity of skeletal muscle, smooth muscle and microfilamentous systems will be employed to determine wheter they block palate shelf rotation in embryo culture. Myosin ATPase reactions of palate sections will be performed and analyzed at the electron microscopic level. BIBLIOGRAPHIC REFERENCES: Babiarz, B.S., Allenspach, A.L. and Zimmerman, E.F. Ultrastructural Evidence of Contractile Systems in Mouse Palates Prior to Rotation. Devel. Biol., 47:32-44 (1975). Zimmerman, E.F. Chemical Structure and Teratogenic Mechanism of Action. In Environmental Agents and Congenital Defects. Methods for Detection. Shepard, T.H., Miller, J.R. and Marois, M. Eds. Chap. 7 pp. 79-88 (1975).